bpo-41324 Add a minimal decimal capsule API (#21519)

3 files changed, 505 insertions, 7 deletions

diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index fb4e020f126..e7c44acba02 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008-2012 Stefan Krah. All rights reserved.
+ * Copyright (c) 2008-2020 Stefan Krah. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -33,6 +33,8 @@
 
 #include <stdlib.h>
 
+#define CPYTHON_DECIMAL_MODULE
+#include "pydecimal.h"
 #include "docstrings.h"
 
 
@@ -5555,6 +5557,160 @@ static PyTypeObject PyDecContext_Type =
 };
 
 
+/****************************************************************************/
+/*                                   C-API                                  */
+/****************************************************************************/
+
+static void *_decimal_api[CPYTHON_DECIMAL_MAX_API];
+
+/* Simple API */
+static int
+PyDec_TypeCheck(const PyObject *v)
+{
+    return PyDec_Check(v);
+}
+
+static int
+PyDec_IsSpecial(const PyObject *v)
+{
+    if (!PyDec_Check(v)) {
+        PyErr_SetString(PyExc_TypeError,
+            "PyDec_IsSpecial: argument must be a Decimal");
+        return -1;
+    }
+
+    return mpd_isspecial(MPD(v));
+}
+
+static int
+PyDec_IsNaN(const PyObject *v)
+{
+    if (!PyDec_Check(v)) {
+        PyErr_SetString(PyExc_TypeError,
+            "PyDec_IsNaN: argument must be a Decimal");
+        return -1;
+    }
+
+    return mpd_isnan(MPD(v));
+}
+
+static int
+PyDec_IsInfinite(const PyObject *v)
+{
+    if (!PyDec_Check(v)) {
+        PyErr_SetString(PyExc_TypeError,
+            "PyDec_IsInfinite: argument must be a Decimal");
+        return -1;
+    }
+
+    return mpd_isinfinite(MPD(v));
+}
+
+static int64_t
+PyDec_GetDigits(const PyObject *v)
+{
+    if (!PyDec_Check(v)) {
+        PyErr_SetString(PyExc_TypeError,
+            "PyDec_GetDigits: argument must be a Decimal");
+        return -1;
+    }
+
+    return MPD(v)->digits;
+}
+
+static mpd_uint128_triple_t
+PyDec_AsUint128Triple(const PyObject *v)
+{
+    if (!PyDec_Check(v)) {
+        mpd_uint128_triple_t triple = { MPD_TRIPLE_ERROR, 0, 0, 0, 0 };
+        PyErr_SetString(PyExc_TypeError,
+            "PyDec_AsUint128Triple: argument must be a Decimal");
+        return triple;
+    }
+
+    return mpd_as_uint128_triple(MPD(v));
+}
+
+static PyObject *
+PyDec_FromUint128Triple(const mpd_uint128_triple_t *triple)
+{
+    PyObject *context;
+    PyObject *result;
+    uint32_t status = 0;
+
+    CURRENT_CONTEXT(context);
+
+    result = dec_alloc();
+    if (result == NULL) {
+        return NULL;
+    }
+
+    if (mpd_from_uint128_triple(MPD(result), triple, &status) < 0) {
+        if (dec_addstatus(context, status)) {
+            Py_DECREF(result);
+            return NULL;
+        }
+    }
+
+    return result;
+}
+
+/* Advanced API */
+static PyObject *
+PyDec_Alloc(void)
+{
+    return dec_alloc();
+}
+
+static mpd_t *
+PyDec_Get(PyObject *v)
+{
+    if (!PyDec_Check(v)) {
+        PyErr_SetString(PyExc_TypeError,
+            "PyDec_Get: argument must be a Decimal");
+        return NULL;
+    }
+
+    return MPD(v);
+}
+
+static const mpd_t *
+PyDec_GetConst(const PyObject *v)
+{
+    if (!PyDec_Check(v)) {
+        PyErr_SetString(PyExc_TypeError,
+            "PyDec_GetConst: argument must be a Decimal");
+        return NULL;
+    }
+
+    return MPD(v);
+}
+
+static PyObject *
+init_api(void)
+{
+    /* Simple API */
+    _decimal_api[PyDec_TypeCheck_INDEX] = (void *)PyDec_TypeCheck;
+    _decimal_api[PyDec_IsSpecial_INDEX] = (void *)PyDec_IsSpecial;
+    _decimal_api[PyDec_IsNaN_INDEX] = (void *)PyDec_IsNaN;
+    _decimal_api[PyDec_IsInfinite_INDEX] = (void *)PyDec_IsInfinite;
+    _decimal_api[PyDec_GetDigits_INDEX] = (void *)PyDec_GetDigits;
+    _decimal_api[PyDec_AsUint128Triple_INDEX] = (void *)PyDec_AsUint128Triple;
+    _decimal_api[PyDec_FromUint128Triple_INDEX] = (void *)PyDec_FromUint128Triple;
+
+    /* Advanced API */
+    _decimal_api[PyDec_Alloc_INDEX] = (void *)PyDec_Alloc;
+    _decimal_api[PyDec_Get_INDEX] = (void *)PyDec_Get;
+    _decimal_api[PyDec_GetConst_INDEX] = (void *)PyDec_GetConst;
+
+    return PyCapsule_New(_decimal_api, "_decimal._API", NULL);
+}
+
+
+/****************************************************************************/
+/*                                  Module                                  */
+/****************************************************************************/
+
 static PyMethodDef _decimal_methods [] =
 {
   { "getcontext", (PyCFunction)PyDec_GetCurrentContext, METH_NOARGS, doc_getcontext},
@@ -5665,17 +5821,27 @@ PyInit__decimal(void)
     DecCondMap *cm;
     struct ssize_constmap *ssize_cm;
     struct int_constmap *int_cm;
+    static PyObject *capsule = NULL;
+    static int initialized = 0;
     int i;
 
 
     /* Init libmpdec */
-    mpd_traphandler = dec_traphandler;
-    mpd_mallocfunc = PyMem_Malloc;
-    mpd_reallocfunc = PyMem_Realloc;
-    mpd_callocfunc = mpd_callocfunc_em;
-    mpd_free = PyMem_Free;
-    mpd_setminalloc(_Py_DEC_MINALLOC);
+    if (!initialized) {
+        mpd_traphandler = dec_traphandler;
+        mpd_mallocfunc = PyMem_Malloc;
+        mpd_reallocfunc = PyMem_Realloc;
+        mpd_callocfunc = mpd_callocfunc_em;
+        mpd_free = PyMem_Free;
+        mpd_setminalloc(_Py_DEC_MINALLOC);
+
+        capsule = init_api();
+        if (capsule == NULL) {
+            return NULL;
+        }
 
+        initialized = 1;
+    }
 
     /* Init external C-API functions */
     _py_long_multiply = PyLong_Type.tp_as_number->nb_multiply;
@@ -5900,6 +6066,11 @@ PyInit__decimal(void)
     CHECK_INT(PyModule_AddStringConstant(m, "__version__", "1.70"));
     CHECK_INT(PyModule_AddStringConstant(m, "__libmpdec_version__", mpd_version()));
 
+    /* Add capsule API */
+    Py_INCREF(capsule);
+    if (PyModule_AddObject(m, "_API", capsule) < 0) {
+        goto error;
+    }
 
     return m;
 
diff --git a/Modules/_decimal/tests/deccheck.py b/Modules/_decimal/tests/deccheck.py
index 5d9179e6168..15f104dc463 100644
--- a/Modules/_decimal/tests/deccheck.py
+++ b/Modules/_decimal/tests/deccheck.py
@@ -49,6 +49,9 @@ from randdec import unary_optarg, binary_optarg, ternary_optarg
 from formathelper import rand_format, rand_locale
 from _pydecimal import _dec_from_triple
 
+from _testcapi import decimal_as_triple
+from _testcapi import decimal_from_triple
+
 C = import_fresh_module('decimal', fresh=['_decimal'])
 P = import_fresh_module('decimal', blocked=['_decimal'])
 EXIT_STATUS = 0
@@ -154,6 +157,45 @@ TernaryRestricted = ['__pow__', 'context.power']
 
 
 # ======================================================================
+#                            Triple tests
+# ======================================================================
+
+def c_as_triple(dec):
+    sign, hi, lo, exp = decimal_as_triple(dec)
+
+    coeff = hi * 2**64 + lo
+    return (sign, coeff, exp)
+
+def c_from_triple(triple):
+    sign, coeff, exp = triple
+
+    hi = coeff // 2**64
+    lo = coeff % 2**64
+    return decimal_from_triple((sign, hi, lo, exp))
+
+def p_as_triple(dec):
+    sign, digits, exp = dec.as_tuple()
+
+    s = "".join(str(d) for d in digits)
+    coeff = int(s) if s else 0
+
+    if coeff < 0 or coeff >= 2**128:
+        raise ValueError("value out of bounds for a uint128 triple");
+
+    return (sign, coeff, exp)
+
+def p_from_triple(triple):
+    sign, coeff, exp = triple
+
+    if coeff < 0 or coeff >= 2**128:
+        raise ValueError("value out of bounds for a uint128 triple");
+
+    digits = tuple(int(c) for c in str(coeff))
+
+    return P.Decimal((sign, digits, exp))
+
+
+# ======================================================================
 #                            Unified Context
 # ======================================================================
 
@@ -846,12 +888,44 @@ def verify(t, stat):
         t.presults.append(str(t.rp.imag))
         t.presults.append(str(t.rp.real))
 
+        ctriple = None
+        if t.funcname not in ['__radd__', '__rmul__']: # see skip handler
+            try:
+                ctriple = c_as_triple(t.rc)
+            except ValueError:
+                try:
+                    ptriple = p_as_triple(t.rp)
+                except ValueError:
+                    pass
+                else:
+                    raise RuntimeError("ValueError not raised")
+            else:
+                cres = c_from_triple(ctriple)
+                t.cresults.append(ctriple)
+                t.cresults.append(str(cres))
+
+                ptriple = p_as_triple(t.rp)
+                pres = p_from_triple(ptriple)
+                t.presults.append(ptriple)
+                t.presults.append(str(pres))
+
         if t.with_maxcontext and isinstance(t.rmax, C.Decimal):
             t.maxresults.append(t.rmax.to_eng_string())
             t.maxresults.append(t.rmax.as_tuple())
             t.maxresults.append(str(t.rmax.imag))
             t.maxresults.append(str(t.rmax.real))
 
+            if ctriple is not None:
+                # NaN payloads etc. depend on precision and clamp.
+                if all_nan(t.rc) and all_nan(t.rmax):
+                    t.maxresults.append(ctriple)
+                    t.maxresults.append(str(cres))
+                else:
+                    maxtriple = c_as_triple(t.rmax)
+                    maxres = c_from_triple(maxtriple)
+                    t.maxresults.append(maxtriple)
+                    t.maxresults.append(str(maxres))
+
         nc = t.rc.number_class().lstrip('+-s')
         stat[nc] += 1
     else:
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index fca94a83a5d..593034ef65e 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -19,6 +19,7 @@
 
 #include "Python.h"
 #include "datetime.h"
+#include "pydecimal.h"
 #include "marshal.h"
 #include "structmember.h"         // PyMemberDef
 #include <float.h>
@@ -2705,6 +2706,252 @@ test_PyDateTime_DELTA_GET(PyObject *self, PyObject *obj)
     return Py_BuildValue("(lll)", days, seconds, microseconds);
 }
 
+/* Test decimal API */
+static int decimal_initialized = 0;
+static PyObject *
+decimal_is_special(PyObject *module, PyObject *dec)
+{
+    int is_special;
+
+    (void)module;
+    if (!decimal_initialized) {
+       if (import_decimal() < 0) {
+            return NULL;
+       }
+
+       decimal_initialized = 1;
+    }
+
+    is_special = PyDec_IsSpecial(dec);
+    if (is_special < 0) {
+        return NULL;
+    }
+
+    return PyBool_FromLong(is_special);
+}
+
+static PyObject *
+decimal_is_nan(PyObject *module, PyObject *dec)
+{
+    int is_nan;
+
+    (void)module;
+    if (!decimal_initialized) {
+       if (import_decimal() < 0) {
+            return NULL;
+       }
+
+       decimal_initialized = 1;
+    }
+
+    is_nan = PyDec_IsNaN(dec);
+    if (is_nan < 0) {
+        return NULL;
+    }
+
+    return PyBool_FromLong(is_nan);
+}
+
+static PyObject *
+decimal_is_infinite(PyObject *module, PyObject *dec)
+{
+    int is_infinite;
+
+    (void)module;
+    if (!decimal_initialized) {
+       if (import_decimal() < 0) {
+            return NULL;
+       }
+
+       decimal_initialized = 1;
+    }
+
+    is_infinite = PyDec_IsInfinite(dec);
+    if (is_infinite < 0) {
+        return NULL;
+    }
+
+    return PyBool_FromLong(is_infinite);
+}
+
+static PyObject *
+decimal_get_digits(PyObject *module, PyObject *dec)
+{
+    int64_t digits;
+
+    (void)module;
+    if (!decimal_initialized) {
+       if (import_decimal() < 0) {
+            return NULL;
+       }
+
+       decimal_initialized = 1;
+    }
+
+    digits = PyDec_GetDigits(dec);
+    if (digits < 0) {
+        return NULL;
+    }
+
+    return PyLong_FromLongLong(digits);
+}
+
+static PyObject *
+decimal_as_triple(PyObject *module, PyObject *dec)
+{
+    PyObject *tuple = NULL;
+    PyObject *sign, *hi, *lo;
+    mpd_uint128_triple_t triple;
+
+    (void)module;
+    if (!decimal_initialized) {
+       if (import_decimal() < 0) {
+            return NULL;
+       }
+
+       decimal_initialized = 1;
+    }
+
+    triple = PyDec_AsUint128Triple(dec);
+    if (triple.tag == MPD_TRIPLE_ERROR && PyErr_Occurred()) {
+        return NULL;
+    }
+
+    sign = PyLong_FromUnsignedLong(triple.sign);
+    if (sign == NULL) {
+        return NULL;
+    }
+
+    hi = PyLong_FromUnsignedLongLong(triple.hi);
+    if (hi == NULL) {
+        Py_DECREF(sign);
+        return NULL;
+    }
+
+    lo = PyLong_FromUnsignedLongLong(triple.lo);
+    if (lo == NULL) {
+        Py_DECREF(hi);
+        Py_DECREF(sign);
+        return NULL;
+    }
+
+    switch (triple.tag) {
+    case MPD_TRIPLE_QNAN:
+        assert(triple.exp == 0);
+        tuple = Py_BuildValue("(OOOs)", sign, hi, lo, "n");
+        break;
+
+    case MPD_TRIPLE_SNAN:
+        assert(triple.exp == 0);
+        tuple = Py_BuildValue("(OOOs)", sign, hi, lo, "N");
+        break;
+
+    case MPD_TRIPLE_INF:
+        assert(triple.hi == 0);
+        assert(triple.lo == 0);
+        assert(triple.exp == 0);
+        tuple = Py_BuildValue("(OOOs)", sign, hi, lo, "F");
+        break;
+
+    case MPD_TRIPLE_NORMAL:
+        tuple = Py_BuildValue("(OOOL)", sign, hi, lo, triple.exp);
+        break;
+
+    case MPD_TRIPLE_ERROR:
+        PyErr_SetString(PyExc_ValueError,
+            "value out of bounds for a uint128 triple");
+        break;
+
+    default:
+        PyErr_SetString(PyExc_RuntimeError,
+            "decimal_as_triple: internal error: unexpected tag");
+        break;
+    }
+
+    Py_DECREF(lo);
+    Py_DECREF(hi);
+    Py_DECREF(sign);
+
+    return tuple;
+}
+
+static PyObject *
+decimal_from_triple(PyObject *module, PyObject *tuple)
+{
+    mpd_uint128_triple_t triple = { MPD_TRIPLE_ERROR, 0, 0, 0, 0 };
+    PyObject *exp;
+    unsigned long sign;
+
+    (void)module;
+    if (!decimal_initialized) {
+       if (import_decimal() < 0) {
+            return NULL;
+       }
+
+       decimal_initialized = 1;
+    }
+
+    if (!PyTuple_Check(tuple)) {
+        PyErr_SetString(PyExc_TypeError, "argument must be a tuple");
+        return NULL;
+    }
+
+    if (PyTuple_GET_SIZE(tuple) != 4) {
+        PyErr_SetString(PyExc_ValueError, "tuple size must be 4");
+        return NULL;
+    }
+
+    sign = PyLong_AsUnsignedLong(PyTuple_GET_ITEM(tuple, 0));
+    if (sign == (unsigned long)-1 && PyErr_Occurred()) {
+        return NULL;
+    }
+    if (sign > UINT8_MAX) {
+        PyErr_SetString(PyExc_ValueError, "sign must be 0 or 1");
+        return NULL;
+    }
+    triple.sign = (uint8_t)sign;
+
+    triple.hi = PyLong_AsUnsignedLongLong(PyTuple_GET_ITEM(tuple, 1));
+    if (triple.hi == (unsigned long long)-1 && PyErr_Occurred()) {
+        return NULL;
+    }
+
+    triple.lo = PyLong_AsUnsignedLongLong(PyTuple_GET_ITEM(tuple, 2));
+    if (triple.lo == (unsigned long long)-1 && PyErr_Occurred()) {
+        return NULL;
+    }
+
+    exp = PyTuple_GET_ITEM(tuple, 3);
+    if (PyLong_Check(exp)) {
+        triple.tag = MPD_TRIPLE_NORMAL;
+        triple.exp = PyLong_AsLongLong(exp);
+        if (triple.exp == -1 && PyErr_Occurred()) {
+            return NULL;
+        }
+    }
+    else if (PyUnicode_Check(exp)) {
+        if (PyUnicode_CompareWithASCIIString(exp, "F") == 0) {
+            triple.tag = MPD_TRIPLE_INF;
+        }
+        else if (PyUnicode_CompareWithASCIIString(exp, "n") == 0) {
+            triple.tag = MPD_TRIPLE_QNAN;
+        }
+        else if (PyUnicode_CompareWithASCIIString(exp, "N") == 0) {
+            triple.tag = MPD_TRIPLE_SNAN;
+        }
+        else {
+            PyErr_SetString(PyExc_ValueError, "not a valid exponent");
+            return NULL;
+        }
+    }
+    else {
+        PyErr_SetString(PyExc_TypeError, "exponent must be int or string");
+        return NULL;
+    }
+
+    return PyDec_FromUint128Triple(&triple);
+}
+
 /* test_thread_state spawns a thread of its own, and that thread releases
  * `thread_done` when it's finished.  The driver code has to know when the
  * thread finishes, because the thread uses a PyObject (the callable) that
@@ -5314,6 +5561,12 @@ static PyMethodDef TestMethods[] = {
     {"PyDateTime_DATE_GET",        test_PyDateTime_DATE_GET,      METH_O},
     {"PyDateTime_TIME_GET",        test_PyDateTime_TIME_GET,      METH_O},
     {"PyDateTime_DELTA_GET",       test_PyDateTime_DELTA_GET,     METH_O},
+    {"decimal_is_special",      decimal_is_special,              METH_O},
+    {"decimal_is_nan",          decimal_is_nan,                  METH_O},
+    {"decimal_is_infinite",     decimal_is_infinite,             METH_O},
+    {"decimal_get_digits",      decimal_get_digits,              METH_O},
+    {"decimal_as_triple",       decimal_as_triple,               METH_O},
+    {"decimal_from_triple",     decimal_from_triple,             METH_O},
     {"test_list_api",           test_list_api,                   METH_NOARGS},
     {"test_dict_iteration",     test_dict_iteration,             METH_NOARGS},
     {"dict_getitem_knownhash",  dict_getitem_knownhash,          METH_VARARGS},